PROGRESS TOWARDS DEVELOPING NATIONAL GEOLOGICAL DATABASES

A ten-year effort at the USGS is underway to develop national-scale integrated digital databases for four themes: bedrock geology, regional geochemistry, aeromagnetic and gravity data, and mineral deposit information. We collaborate with state agencies and the minerals industry to update mineral deposit records, collect stream-sediment samples, and develop digital state geologic maps. Data are released through the website: http://mrdata.usgs.gov (select Download Data to see currently available data).

We are entering the 8th year of this effort and we have nearly completed acquisition of state-scale geologic maps. In some cases, USGS contracts with state agencies have resulted in the updating or creation of digital state bedrock geologic maps. Surficial geology is compiled where available. A national compilation of geologic map databases necessitates development of uniform data structures. Database development is progressing and uniform attribution of the geologic data (including geologic units, lithologies, ages, contacts) for each state is underway.

Another important goal is the development of a national geochemical database of stream-sediment samples. Using existing and new samples collected on a grid (roughly 17 x 17 km) throughout the country (including Alaska and Hawaii), we have analyzed or reanalyzed about 54,000 samples using one set of analytical techniques. We expect to have analyzed more than 60,000 samples at the completion of this effort. A number of geochemical anomalies related to natural causes and human impact have become apparent, providing a rich framework for new, more detailed studies.

A continent-wide aeromagnetic compilation, the Magnetic Anomaly Map of North America, was released in 2002. More detailed compilations of available aeromagnetic and gravity surveys for individual states are being prepared for release via the web. We have supported the acquisition of new aeromagnetic and gravity data in Alaska and Wisconsin and the preparation of the state compilations.

Records providing geologic information for significant mineral deposits in the US will be updated and entered into the USGS Mineral Resources Data System (MRDS). So far, new data on more than 14,000 mineral occurrences have been collected through contracts with state agencies and mineral industry consultants.